package com.ccloud.common.core.utils;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Lazy;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;

/**
 * Spring的ApplicationContext的持有者,可以用静态方法的方式获取spring容器中的bean
 */
@Component
@Order(1)
@Lazy(false)
public class SpringContextUtils implements ApplicationContextAware, DisposableBean {

    private static ApplicationContext applicationContext;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        SpringContextUtils.applicationContext = applicationContext;
    }

    public static ApplicationContext getApplicationContext() {
        assertApplicationContext();
        return applicationContext;
    }


    @SuppressWarnings("unchecked")
    public static <T> T getBean(String beanName) {
        assertApplicationContext();
        return (T) applicationContext.getBean(beanName);
    }

    public static <T> T getBean(Class<T> requiredType) {
        assertApplicationContext();
        return applicationContext.getBean(requiredType);
    }


    /**
     * 获取HttpServletRequest
     */
    public static HttpServletRequest getHttpServletRequest() {
        RequestAttributes attr = RequestContextHolder.getRequestAttributes();
        if (attr == null) {
            return null;
        }
        return ((ServletRequestAttributes) attr).getRequest();
    }


    private static void assertApplicationContext() {
        if (SpringContextUtils.applicationContext == null) {
            throw new RuntimeException("applicaitonContext属性为null,请检查是否注入了SpringContextUtils!");
        }
    }

    public static void clearHolder() {
        applicationContext = null;
    }

    @Override
    public void destroy() throws Exception {
        SpringContextUtils.clearHolder();
    }

}
